I would no longer say "the dominant force", but still "a major force." After losing the elections in 2000 to the Conservative PAN party, they managed to win the presidency in 2012. They are still one of the bigger political parties due to their history in power. They have ebbed in power since the 2018 election, but seeing as many analysts expected the party to collapse after 2000 election, I would say it is too early to call for its demise. I think it still has a strong base of supporters within the general populace, government and certainly within Mexican business.
It doesn't appear that it is going to collapse as the Communist Parties did in Eastern Europe, but its support could continue to erode as many of the mainstream European political parties have. Most of these have continued to dominate in some form or fashion as I expect the PRI to as well, but in a less dominant fashion.